The present invention is directed to a method and system simulating altitude changes in an enclosed space, and particularly, is directed to a method and system in which ambient oxygen and carbon dioxide levels are monitored and adjusted to provide desired physiological benefits derived from a person or animal spending time in an altitude environment to improve athletic performance and/or to relieve altitude sickness symptoms for other individuals. High and low oxygen environments affect the physiology in different ways providing health and athletic benefits.
Going to a higher altitude or reduced oxygen environments is safe when done properly. Millions of air travelers experience high altitude when they fly in aircraft pressurized to 6-8,000 feet. Hundreds of thousands of tourists visit Colorado""s high country and stay at altitudes ranging from 8,000 feet (Vail or Aspen, Colo., USA) to 11,000 feet (Leadville, Colo., USA). These same tourists enjoy shorter stays at 12,000 feet (top of Loveland Pass) to 14,000 feet (top of Pikes Peak).
However, medical problems due to high altitude include a number of uncomfortable symptoms and some potentially dangerous conditions, all resulting from the decrease in the oxygen concentration in the blood. Altitude sickness is not a specific disease but is a term applied to a group of rather widely varying symptoms caused by altitude. The primary cause is decreased oxygen. People react differently to altitude at different times and different people react differently to altitude. Physical fitness does not confer any protection against acute mountain sickness and does not facilitate acclimatization. Altitude effects result from the lower oxygen content of the airxe2x80x94not from the lower barometric pressure. At 18,000 feet the amount of oxygen molecules per cubic foot of air is approximately one half that of sea level.
Additionally, going too high too fast causes altitude sickness. When a person is exposed to a higher altitude for longer periods, he/she acclimatizes to the higher altitude. By acclimatizing slowly, a person can usually avoid the symptoms of altitude sickness. Symptoms of altitude sickness may include: nausea, headaches, sleeplessness, weakness, malaise, difficulty breathing, feeling xe2x80x9chung overxe2x80x9d, lethargy, a loss of appetite, altered thinking, and/or feeling xe2x80x9cintoxicatedxe2x80x9d.
During acclimatization there is an increase the body""s efficiency in absorbing, transporting, delivering and utilizing oxygen. The most important processes in acclimatization are:
(a) An increase in respiratory rate and volume. This change usually begins at around 3,000 feet and may not reach a constant value until several days after arrival at high altitude.
(b) Changes in the pulmonary circulation. During exposure to any kind of low oxygen environment, including high altitude, the pressure in the pulmonary arteries is elevated and the capillaries of the lung are more fully infused with blood increasing the capacity of the circulatory bed of the lung to absorb oxygen.
(c) An increase in the number of red blood cells. Shortly after arrival at high altitude an increase in the number of red blood cells in the blood occurs. Later red blood cell production by the bone marrow is increased so that the blood contains more red cells than at sea level. Since the red cells carry oxygen the increased number of red cells permits each unit of blood to carry more oxygen. This process reaches its maximum in about six weeks.
(d) Increased cardiac output. During the first few days at high altitude, the volume of blood pumped by the heart per minute is increased, which increases the rate of oxygen delivery to the tissues.
(e) Changes in the tissues of the body. Prolonged exposure to altitude is accompanied by the changes in the tissues that use oxygen, particularly muscle, which permit normal function at very low oxygen pressures. These changes include an increase in the number of capillaries within the tissue, and an increase in the concentration of enzymes, which extract oxygen from hemoglobin, as well as an increase in the volume of mitochondria, which are the cellular structures within which these enzymes are located.
The physiological effects of altitude acclimatization have been documented for many years. These effects include:
(a) An increase in total blood volume
(b) An increase in red blood cell mass
(c) An increase in VO2 maxxe2x80x94the maximum amount of oxygen the body can convert to work
(d) An increase in hematocrit, the ratio of red blood cells to total blood volume
(e) An increase in the lungs ability to exchange gases efficiently
Together these changes produce an increase in the oxygen carrying capacity of the blood and the body""s ability to use the oxygen transported resulting in a major difference in the body""s ability to perform work both at altitude and at sea level. The net result of such changes is an improvement in athletic performance.
The time required for the different adaptive processes is variable. The respiratory and biochemical changes are typically complete in six to eight days. The increase in the number of red blood cells is about 90 percent of maximum at three weeks. In general, about 80% of adaptation is completed by 10 days and 95% is completed in six weeks. Longer periods of acclimatization result in only minor increases in high altitude performance. However, continued exposure to altitude does maintain the physiological acclimatization. After return to sea level, acclimatization starts to be lost after 10-15 days. Red blood cell counts remain higher for up to 6 weeks.
Living at a high altitude is essential to maximize the oxygen carrying capacity of the blood and improving athletic performance. In their landmark study published in the July 1997 issue of the Journal of Applied Physiology, Dr Benjamin Levine and Dr. James Strey-Gundersen of the University of Texas Southwestern Medical Center demonstrated convincingly that athletes perform best when living (including sleeping) at high altitude and training at low altitude. Their study of 39 elite runners showed a marked increase in performance (at sea level as well as at altitude) among the group that lived at high altitude and drove down to low altitude for training. There was no performance improvement in any of the other groups (living high and training high, living low training low, or living low and training high.).
Further studies have also shown that training at low altitude is critical to getting the best quality training. At high altitude the blood is not fully saturated with oxygen. While the athlete""s blood would be 97-98% saturated with oxygen at sea level it may be only 80% saturated at 14,000 feet. As a result the athlete at altitude is unable to work or train as hard. U.S. Olympic Team cyclists at their high altitude training camp found they could work harder by riding cycling ergometers while wearing oxygen masks to simulate sea level. A rider that could put out 400 watts at altitude could put out 480 watts at sea level with the same perceived exertion. In short, athletes benefit more from their training at sea level than from training at high altitude. This study and others show that the optimal training program includes living high and training low.
Research shows that the body""s production of erythropoietin (the natural glycoprotein produced by the kidneys that signals the bone marrow to make more red blood cells) goes up dramatically as altitude increases from 6,000 feet (30% increase over sea level) to 14,500 feet (300% increase over sea level.) Most training regimens simply do not train the athlete at low enough elevations while allowing them to sleep at high enough elevations to gain the maximum benefit from training. In a preferred embodiment, it is recommended that a person sleep at an altitude of 8,000-13,000 feet for the maximum acclimatization effect, after a period of acclimatization at lower altitudes.
What limits exercise at high altitude is the lack of oxygen concentration. Mountain air contains less oxygen than air at sea level. By reducing the amount of oxygen in the room the equipment simulates high altitude.
The amount of exercise that can be performed at high altitude is less than at sea level and the heart rate reached during maximal exercise is less. This indicates less cardiac work. Maximal exercise capacity decreases progressively with higher altitudes. So it would be desirable to sleep high and train low.
The beneficial effect of sleeping high and training low is that the oxygen processing capacity of the body is increased. This allows the body to do more work (run, swim, ski, or cycle faster) at the same level of physical exertion and heart rate. The body can also perform the same amount of work as it did prior to living high and training low at lower exertion rates and lower heart rates. The athlete can remain in an aerobic state longer and work harder without becoming anaerobic. The athlete can perform at higher levels while still using fat as a fuel instead of sugars. This allows for greater performance levels and faster times while decreasing lactic acid production.
Research has also shown that athletes who train at low altitude but live at high altitude perform better in endurance, and running speed, than athletes who train and live at high altitude or who live and train at low altitude. xe2x80x9cHigh-lowxe2x80x9d athletes also recover faster and increase their VO2 max. Moreover, when people plan to participate in an athletic event at high altitude it is desirable to train at high altitude before the event to acclimatize to the conditions. Therefore, there is a need to simulate both high altitudes and low altitudes.
There have been various attempts at providing systems for simulating a different altitude from the altitude that a person resides in order to presumably address the debilitating effects of increased altitude, and/or to obtain some of the advantages of purposely simulating different altitudes for, e.g., athletic training. Some of these are discussed immediately below.
Heiki Rusko in Finland introduced nitrogen into an enclosed house using bottled nitrogen to reduce oxygen levels in an altitude house. This approach suffered from high cost, low convenience and an inability to control CO2. Only high altitude was simulated, not low altitude.
Nils Ottestad in Norway improved upon this concept by using an oxygen concentrator, a magnetic gate, a fan, a CO2 scrubber, oxygen sensors, and CO2 sensors. In his invention, the oxygen concentrator was running at all times. A user activated the CO2 scrubber. Oxygen sensors measured oxygen levels and sent data to a control panel that only controlled the alarm, the magnetic gate, and a fan. This approach suffered from requiring the user to control the CO2 scrubber and a general lack of sophistication. The control panel did not control the oxygen concentrator, the CO2 scrubber, or the high CO2 alarm. Fans were not employed in high CO2 situations. Only high altitude was simulated, not low altitude.
Additionally, U.S. Pat. Nos. 5,964,222 filed Dec. 3, 1997, 5,799,652 filed Jul. 21, 1995, 5,924,419 filed Feb. 8, 1997, 5,850,833 filed May 22, 1995, all of which have Kotliar as the inventor, describe the use of an oxygen concentrator to introduce nitrogen into an environment to thereby provide oxygen depleted air. This approach suffers from a limited ability to control altitude and CO2 levels. Moreover, Kotliar""s systems are only capable of simulating high, rather than low altitudes.
Accordingly, it would be desirable to have a more cost effective method and apparatus that could better simulate variable altitudes, and in particular, easily simulate both lower and higher altitudes than the current altitude of a person.
Definition of Terms
Simulated altitude, or physiological altitude is defined to be the partial pressure of oxygen that corresponds to a particular actual altitude. The partial pressure of oxygen is influenced by the oxygen concentration and the atmospheric pressure.
The present invention is referred to herein as a xe2x80x9cColorado Mountain Roomxe2x80x9d (also denoted as CMR herein) and encompasses both a method and a system for adjusting O2 and CO2 levels to provide benefits to, e.g., the training of athletes, the treating or preventing altitude of sickness as well as other altitude or altitude change related conditions. For example, high oxygen environments relieve symptoms of altitude sickness and allow for people to sleep more easily. In one embodiment the Colorado Mountain Room controls oxygen levels in a room, for both allowing the user to simulate high altitudes (low oxygen) for purposes of altitude acclimatization and athletic training, and to simulate low altitude (high oxygen levels) for athletic training. In one embodiment, the Colorado Mountain Room requires a reasonably well sealed environment (a room or enclosure such as a tent). However, alternative embodiments that are xe2x80x9cleakyxe2x80x9d can be provided.
The Colorado Mountain Room may have penetrations through the walls to allow for the passage of hoses, and to allow for the controlled passage of air through a gated penetration. In one embodiment, the present invention includes the following components (i.e., the xe2x80x9cequipmentxe2x80x9d):
(a) A oxygen concentratorxe2x80x94This may be a molecular sieve to separate oxygen and nitrogen molecules. Such a molecular sieve removes approximately 5 liters of oxygen from the room per minute.
(b) A CO2 sensorxe2x80x94this measures the amount of CO2 in the room. CO2 is produced by breathing.
(c) A CO2 scrubberxe2x80x94This eliminates CO2 to keep the air fresh and clean within the CMR.
(d) An oxygen sensorxe2x80x94This measures the amount of oxygen in the room within the CMR.
(e) A temperature sensorxe2x80x94This sensor measures the temperature within the Colorado Mountain Room.
(f) An ambient pressure sensorxe2x80x94This sensor measures the ambient air pressure in the Colorado Mountain Room.
(g) A ventilation fan, a vent, a gate, blower, etc.xe2x80x94This brings in fresh air into CMR when oxygen levels therein fall below desired levels, or carbon dioxide levels rise above desired levels, and if either oxygen or CO2 are outside of their safe range.
(h) A controllerxe2x80x94This controller controls the oxygen concentrator, a CO2 scrubber, and the ventilation fan for altering the percentage of oxygen in the room, removing carbon dioxide, and bringing in fresh air and monitoring oxygen and carbon dioxide levels. If either oxygen or carbon dioxide levels are out of their safe ranges an alarm of the present invention is triggered and the ventilation fan is turned on to bring fresh air into the room. The oxygen sensor, the CO2 sensor, the temperature sensor, and the ambient pressure sensor are also connected to the controller. The computerized controller includes a computer, an analog-to-digital converter module, a relay output module, a viewing panel, and appropriate power supplies. The controller""s computer: (i) activates and deactivates the attached above-identified oxygen concentrator, CO2 scrubber, and ventilation fan, and (ii) displays information on a digital control panel (also denoted a visual display panel herein) using the signals received from the above-identified sensors.
(i) An uninterruptible power sourcexe2x80x94This power source powers the sensors, the control panel and the ventilation fan in case of a power outage.
In one embodiment, the equipment identified above is sized to operate within a tightly sealed room of about 1,000 cubic feet. The ability of the equipment to create an altitude simulation space is dependent on the room""s air infiltration rate and oxygen removal rate, or nitrogen introduction rate of the equipment.